struct wordset

struct wordset
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description

lisence: GNU LGPL, non-substantial parts may promote to any opensource.org approved license.

description: "struct" implements neon/mops/mpe-like structures. "structs" implements fsl/mforth-like structures.

the two wordsets are designed to let the sub-words to be used interchangably both inside STRUCT and STRUCTURE definitions. They will also work inside pfe's class-definitions btw.

The provided words try to be compatible with the simple implementation guidelines as provided in the survey at the comp.lang.forth.repository (http://forth.sourceforge.net/word/structure) and the documentation on MPE' forth's implementation (/vol/c/Programme/PfwVfx/Doc/VfxMan.Htm/struct.html) and the structs-source of the Forth Scientific Library (lib/fsl/structs.fth) plus some compatibility sugar for the gforth' struct (gforth/struct.fs)

field-layout PFA[0] has the offset (elsewhere for the method-table) PFA[1] has the sizeof (may serve as minimalistic type-id)

struct-layout PFA[0] unused (elswehere method-table or type-id) PFA[1] has the sizeof (that is instantiated)

therefore SIZEOF is designed to give a nice result in both places.

EXTENSIONS STRUCT ( "name" -- here zero-offset )( ); ;

begin definition of a new structure (mpe.000)

 : STRUCT CREATE  !CSP
   HERE
   0 DUP ,
 DOES>
   @
 ;

EXTENSIONS END-STRUCT ( here some-offset -- )( ); ;

terminate definition of a new structure (mpe.000)

 : END-STRUCT  SWAP !  ?CSP ;

EXTENSIONS FIELD ( offset size "name" -- offset+size )( ); ;

create a field - the workhorse for both STRUCT and STRUCTURE implementations. The created fieldname is an OFFSET:-word that memorizes the current offset in its PFA and will add that offset on runtime. This forth-word does *not* align.

 : FIELD CREATE
   OVER ,
   +
 DOES>
    @ +
 ;

EXTENSIONS SUBRECORD ( outer-offset "name" -- outer-offset here zero-offset )( ); ;

begin definition of a subrecord (mpe.000)

 : STRUCT CREATE  
   HERE
   0 DUP ,
 DOES>
   @
 ;

EXTENSIONS END-SUBRECORD ( outer-offset here some-offset -- outer-offset+some )( ); ;

end definition of a subrecord (mpe.000)

 : END-SUBRECORD  TUCK SWAP !  + ;

EXTENSIONS ARRAY-OF ( some-offset n len "name" -- some-offset )( ); ;

a FIELD-array

 : ARRAY-OF * FIELD ;

EXTENSIONS VARIANT ( outer-offset "name" -- outer-offset here zero-offset )( ); ;

Variant records describe an alternative view of the current record or subrecord from the start to the current point. The variant need not be of the same length, but the larger is taken

 : VARIANT SUBRECORD ;

EXTENSIONS END-VARIANT ( outer-offset here some-offset -- outer-offset )( ); ;

terminate definition of a new variant (mpe.000)

 : END-STRUCT  TUCK SWAP !  2DUP < IF NIP ELSE DROP THEN ;

EXTENSIONS INSTANCE ( len "name" -- )(); p4:"instance";

Create a named instance of a named structure.

 : INSTANCE  CREATE ALLOT ;

EXTENSIONS INSTANCE-ADDR ( len -- addr )( ); ;

Create nameless instance of a structure and return base address.

 : INSTANCE-ADDR  HERE SWAP ALLOT ;

EXTENSIONS STRUCTURE ( "name" -- here zero-offset )exec( ); ;

start a structure definition

 : STRUCTURE: CREATE !CSP
   HERE
   0 DUP ,
 DOES>
   CREATE @ ALLOT
 ;

FCode_RT (p4_structure_RT)

EXTENSIONS ENDSTRUCTURE ( here some-offset -- )( ); ;

finalize a previously started STRUCTURE definition

 : ENDSTRUCTURE  SWAP !  ?CSP ;

EXTENSIONS SIZEOF ( "name" -- size )(); as:"sizeof";

get the size-value from a previous structure definition

 : SIZEOF   ' >BODY @  STATE @ IF [COMPILE] LITERAL THEN ; IMMEDIATE

FCode_XE (p4_sizeof_XT)

EXTENSIONS CHAR% ( .. )(); as:"char-percent";

ordinary primitive CHAR%